Marian Anderson sung spirituals and folk music, which is obv. how I heard of her. Smoky deep and classically trained, she has the weirdest and prettiest version of Roll Jordan Roll. It's the classical stuff that'll stop your heart though - also she had a big range, so this isn't that deep for her:

Eee. This and if you can find it, her Casta Diva. Enough to turn any girl's head.

And that represents everything I know about classical music, so don't expect any more :D